<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
   *{padding:0;margin:0;}
   .layer1{width:100%;height:200px;background:#C9C;}
   .layer2{width:100%;height:200px;background:#9F6;}
      .layer2-1{width:45%;height:180px;background:#63C;float:left;border-style:solid;border-color:#C90;margin:10px;}
	  .layer2-2{width:45%;height:180px;background:#F0C;float:left;border-style:solid;border-color:#C90;margin:10px;}
	  .layer2-3{clear:both;}
   .layer3{width:100%;height:200px;background:#CF3;}
      .layer3-1{width:100%;height:80px;background:#30C;border-style:solid;border-color:#C90;margin:10px;}
	  .layer3-2{width:100%;height:80px;background:#FF0;border-style:solid;border-color:#C90;margin:10px;}
</style>
</head>

<body>
  <div class="layer1"></div>
  <div class="layer2">
    <div class="layer2-1"></div>
    <div class="layer2-2"></div>
    <div class="layer2-3"></div>
  </div>
  <div class="layer3">
    <div class="layer3-1"></div>
    <div class="layer3-2"></div>
  </div>
</body>
</html>
